Voltage regulator



o. PERRY j 2.236.880

VOLTAGE RBGULATO' Filsd Dec'. 7. 1956 April 1, 1941.

ATTORNEY.

vatcnted pr. l, 1941 UITED STATES ATENT FFCE assess@ vorfrson arrancaron @liver Ai Perry, Los Angeles, Calif. applicaties necemter 7, reas, sei-iai No. nasse 2 Claims.

My invention relates broadly to polyphase alternators and has for its major object the provision oi an improved type of apparatus for regulating or compensating for voltage variations- 'from no load to full load or vice-versa, with no noticeable change in voltage except that caused by change in speed of the rotor betere the power plant governor restores the speed to normal. 'lf there is a permanent speed drcop due to increased load, the voltage loss due to this droop can be corrected for hy adjusting the compensator resistor to give a greater degree of compensation than would otherwise be necessary.'

Another feature of my invention is that it allows the voltage of the alternator to build up with increase in load to compensate for increasing line drop on long lines.

These and other objects and advantages o my -invention will become apparent from the following description of a preferred form thereof and from the accompanying drawing which shows a wiring diagram illustrating my invention used with a three phase synchronous alternator, it 'seing understood of course that my invention is equally applicable to any polyphase alternator.

in the drawing the letter A indicates a threephase alternator of conventional type having a eld F, it being understood that the alternator may be of the rotating armature or rotating field typ-e as desired. Suitable means for exciting the eld is provided and may he in the nature of a separate exciter E, whose eld is designated by the letter E. [fr variable resistance or resistor Ri and a xed resistance are provided in the field circuit of the exciter Three load lines indicated by the numerals 2 and 3 respectively and a neutral line Ll lead from the alternator .a

'in the usual manner.

Load lines l, 2 and El are provided with current transformers E, (i and l respectively Whose secondaries are connected to rectiilers il, 9 and `quirements to insure longer life.

. HEI-M9) il? respectively. The rectiers are preferably of the full Wave dry oxide type oversize for the re- The rectiers are connected in series with their positive terminal connected to the exciter held circuit at C and their negative terminal connected through a resistance R3 to the exciter field circuit at d.

The resistor Rl allows manual adjustment oi the exciter field to secure the proper voltage at no load condition. The resistance R2 serves to cut the exciter held current down to that required for no load excitation and secondly itserves to match the resistance o the rectifier circuit to the requirements of the exciter iield circuit, since the rectier resistance is usually much too high to include directly in the exciter eld circuit. The resistance R3 is for the purpose of limiting the degree of compensation to that required for a given installation.

The transformers E3 and l are designed to give outputs sufficient to allow full or over coinpensation over the entire load range. The secondary voltages of these transformers are proportional to the load currents in the primaries, and While the primary voltages will not add up arithmetically as A. C. voltages, the rectified outputs of the secondaries do add arithmetically, and by doing so, give compensation proportional to the total polyphase current, Without regard to any unbalance of the phases. if all 'governors gave speed regulation without droop, and if all load lines were short, the transformers could be designed to give just the proper' amount of compensation to maintain constant voltage output,

' but as such is never the case, the transformers must be over capacity and then cut down for each specific condition encountered, hy means of a regulating resistance in the rectifier circuit.

ln operation Rl is adjusted so that at no load condition just enough current lows in the exciter eld circuit to give full voltage across the alternator terminals. Some of the exciter field current will of course ovv' through the rectifier circuit, although due to the relatively high resistance or" the rectiers this amount is quite small, probably around 10%- of the total field current. When the alternator starts delivering current to the load the rectier group acts as a voltage generator in series with the exciter field, and as the load on the alternator increases, builds up the voltage applied to the exciter field, and thus compensates tor the inherent load voltage droop of the alternator.

By placing a transformer rectifier in each ci the load lines i, and instant and proper l installations will be apparent to those skilled in the art.

I claim as my invention: l. An instantaneously starting and controlling voltage-regulator system for polyphase alternators having a separate excitenwhich includes:

a current transformer in each phase lead of said alternator; a full-wave dry type rectifier connected across the secondary of each of said transformers, the output of said rectifiers being con-.- nected in series; a resistance connected in series with said rectiiier circuit; a second resistance connected in shunt across said rectifier-resistvoltage of said alternator.

ance circuit and connected in series with the field of said exciter, the output of said rectifier-resistance circuit being connected so as to boost the voltage normally supplied to said field; and a third resistance connected in series with said field, whereby said eld excitation of said exciter 'may be manually controlled to control said alternator output voltage by controlling the ileld excitation of said alternator.

2. An instantaneously starting and controlling voltage-regulator system for separately excited polyphase alternators which includes: -a current transformer in each phase lead oi said alternator; a full-Wave dry" type rectifier connected across the secondary of each of said transformers, said rectiers being connected in series `with each other and in series with the eld excitation circuit of said' exciter to increase said eld ex-` citation; a resistance connected in series with said rectiers; Va second resistance connected'in parallel with said rectifier-resistance circuit; and a third resistance connectedv in series with said eld excitation circuit to control the no-load OLIVER A. PERRY. 

